To paraphrase myself, our borders and our Border Patrol Agents get no respect

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SAN DIEGO — A 17-year-old Mexican was sentenced to 40 years in prison Thursday for murdering a U.S. Border Patrol agent who was lured from his vehicle during an attempted robbery and shot repeatedly in the head.

Defendant Christian Daniel Castro Alvarez, described as a one-time smuggler of illegal immigrants, sat with his head down throughout the hearing, as the wife and sisters of 30-year-old Robert Rosas emotionally described how his execution shattered their lives.

Castro wrote a letter, read in court by the judge, saying he was "extremely sorry" and wished he could turn back the clock.

The sentencing came as a tough, new law in Arizona thrust illegal immigration back into the national spotlight. The law requires local and state law enforcement officers to question people about their immigration status if there's reason to suspect they're in the country illegally.

U.S. District Judge M. James Lorenz said the "cold-blooded killing" of Rosas changed the dynamics along the U.S.-Mexico border by making agents more fearful for their safety.

"Agents now have to question if they will be ambushed," he said.

Alluding to the robbery attempt, Lorenz said Border Patrol agents must now worry about being attacked "over night-vision goggles or some other ridiculous thing."

Uniformed Border Patrol agents and family members of Rosas in the packed courtroom burst into applause after the judge announced the sentence.

The circumstances of the killing were not entirely clear.

Rosas was shot eight times in the head, neck and torso while on solo patrol the night of July 23, 2009 in a rugged, remote mountainous area near Campo, about 60 miles east of San Diego. He was shot repeatedly from behind.

His body was found with his wallet less than 100 yards from the border. His vehicle was nearby with the engine running and headlights on.

Britt Craig, a civilian who monitors the border for illegal activity and calls the Border Patrol with anything suspicious, told reporters he spoke with Rosas about 15 minutes before the execution.

The agent said he was tracking four people seen walking along the Mexican side of the border fence, apparently preparing to enter the United States illegally.

"He said, 'Yeah, we're going to catch those guys. I'll come back and tell you about it,'" Craig said.

Castro told authorities he and his collaborators lured Rosas out of his vehicle by leaving footprints on a dirt road, shaking bushes and making noise. Castro said he was holding Rosas at gunpoint when the agent reached for Castro's firearm.

Castro, then 16, said he shot once and shouted to his collaborators for help as they walked toward Rosas' vehicle. They turned and opened fire.

Castro said one of his collaborators shot him in the hand, leaving a trail of blood back to Mexico. Castro's DNA matched the blood.

Authorities believe the suspects fled back to Mexico through a small crevice under a border fence made of corrugated metal

Castro surrendered to authorities at a San Diego border crossing in August, less than a month after Rosas died, but the arrest was not announced until Castro pleaded guilty three months later after being charged as an adult.

His attorney Ezekiel Cortez said Castro had two collaborators who are now in Mexico. No other arrests have been announced.

"There are two people somewhere in Mexico that should be hearing this," Cortez said. "These are the two that brutally committed this murder."

Debra Hartman, a spokeswoman for the U.S. attorney's office, declined to comment on any other possible suspects.

The judge said Castro told authorities he was threatened with death if he didn't participate in the robbery or if he didn't leave Tijuana, Mexico, after Rosas was killed. The judge didn't say who may have threatened the teenager.

Castro was raised in a one-room shack and abandoned by his parents by the time he was 12. At one point, he smuggled illegal immigrants, the judge said.

Rosas was the first Border Patrol agent killed by gunfire since 1998, according to The Officer Down Memorial Page, a website that tracks death of law enforcement officers.

Like many people raised in California's Imperial Valley, Rosas found a career in law enforcement. He was a state prison guard for six years before joining the Border Patrol in 2006.

He is survived his wife, Rosalie, and two young children. Prosecutors wrote the judge last week that the children still run to the front door calling "Papa" when a car pulls up to the house.

His widow's voice trembled as she told the judge how much her husband loved his job and cherished his children. A baseball fanatic, he had looked forward to taking his son to his first professional baseball game.

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